クリップボードを監視してVOICEVOXでテキスト読み上げ

Form1.cs

using System.Media;
using System.Runtime.InteropServices;
using System.Text;
using System.Web;

namespace VOICEVOX_test
{
    public partial class Form1 : Form
    {
        [DllImport("user32.dll")]
        private extern static void AddClipboardFormatListener(IntPtr hwnd);

        [DllImport("user32.dll")]
        private extern static void RemoveClipboardFormatListener(IntPtr hwnd);

        // クリップボード更新
        private const int WM_CLIPBOARDUPDATE = 0x31D;

        public Form1()
        {
            InitializeComponent();

            // クリップボードのリスナーとして登録
            AddClipboardFormatListener(Handle);
        }
        private void Form1_FormClosed(object sender, FormClosedEventArgs e)
        {
            // クリップボードリスナー解除
            RemoveClipboardFormatListener(Handle);
        }
        private async Task<string> PostAudioQuery()
        {
            // URL用に変換
            string talk = HttpUtility.UrlEncode(textBox1.Text);
            // URL
            string url = "http://localhost:50021/audio_query?text=" + talk + "&speaker=1";
            // 送信内容を設定
            var content = new StringContent("", Encoding.UTF8, "application/json");

            using (var client = new HttpClient())
            {
                // 要求送る
                HttpResponseMessage response = await client.PostAsync(url, content);
                // 応答受ける
                string resp = await response.Content.ReadAsStringAsync();

                return resp;
            }
        }
        private async Task<byte[]> PostSynthesis()
        {
            // URL
            string url = "http://localhost:50021/synthesis?speaker=1";
            // 送信内容を設定
            var content = new StringContent(textBox2.Text, Encoding.UTF8, "application/json");

            using (var client = new HttpClient())
            {
                // 要求送る
                HttpResponseMessage response = await client.PostAsync(url, content);
                // 応答受ける
                byte[] resp = await response.Content.ReadAsByteArrayAsync();

                return resp;
            }
        }
        private async void button1_Click(object sender, EventArgs e)
        {
            // VOICEVOXにaudio_query送信
            string json = await PostAudioQuery();
            textBox2.Text = json;
        }
        private async void button2_Click(object sender, EventArgs e)
        {
            // VOICEVOXにsynthesis送信
            byte[] bytes = await PostSynthesis();

            MemoryStream wav = new MemoryStream(bytes);
            SoundPlayer player = new SoundPlayer(wav);
            player.Play();
        }
        protected override void WndProc(ref Message msg)
        {
            switch (msg.Msg)
            {
                case WM_CLIPBOARDUPDATE:
                    OnClipboardUpdate();
                    break;
            }
            base.WndProc(ref msg);
        }
        protected async void OnClipboardUpdate()
        {
            IDataObject clip = Clipboard.GetDataObject();

            // クリップボードに入ったのはテキストか?
            if (clip.GetDataPresent(DataFormats.Text))
            {
                // クリップボードから取得
                textBox1.Text = (string)clip.GetData(DataFormats.Text);

                // VOICEVOXへ
                textBox2.Text = await PostAudioQuery();
                byte[] wave = await PostSynthesis();

                // 再生
                MemoryStream memStream = new MemoryStream(wave);
                SoundPlayer player = new SoundPlayer(memStream);
                player.Play();
            }
        }
    }
}